Thank you for stopping by the Weather Watch 12 Blog! After a warm and very dry June our focus shifts to July and the long range forecast based on the LRC, or Lezak's Recurring Cycle. We use a weather pattern theory called the LRC to make accurate and specific long range forecast weeks and months in advance.

Here are the basics of the theory:

Advertisement

A unique weather pattern sets up every year between October 1st and November 10th

The weather pattern cycles, repeats, and continues through winter, spring and into summer. Identifying the cycle length helps tremendously when making long range weather predictions.

Long term long-wave troughs and ridges become established and also repeat at regular times within the cycle. These dominant repeating features are a clue to where storm systems will reach peak strength, and where they will be their weakest.

The LRC is a fall thru summer pattern! There is a pattern! This LRC pattern's cycle duration has been stated going back to December to be around 46. By looking back at previous parts of the pattern we can project forward. A great example is the hot spells that occurred in June were pinpointed using the LRC as far back as April. In late May we also called for dry and hot weather around the 4th of July.

As the sun rises on July, let's use the LRC to breakdown what you can expect.

July 1-7

The first week of July is upon us. Again we called for the heat to continue into the first week of July back in May. Rain chances look low, but a few showers or t-storms are possible as heat surges north July 2 or 3. Heat peaks either July 5 or 6. Cooler weather begins to return to close period. Winds will likely shift off Lake Michigan around July 7, this relates to the pattern around May 21-22.

July 8-16

This period has the potential to be the most active of the entire month. Cooler temperatures will start this stretch and continue into about July 9. Temperatures then bounce around with a chance of rain July 10-12(won't rain all of these days).

Warm/hot temperatures will return around July 12-14 with highs in the 90s possible. This warm-up will precede one of the best precipitation producing parts of this years LRC. A storm system is expected to move into the Midwest around July 15-16. This system represents the best and potentially most widespread rain chance the first half of July.

This system can be traced back to April 16 and May 31. The 500mb map from April 16, 2012 is shown below. Notice the upper low over Minnesota.

This same system cycled through the pattern right on schedule returning to close May. The 500mb map from May 31, 2012 is shown below. Again, upper level low pressure was over Minnesota.

Even though our overall atmospheric flow is weaker, and farther north in July, expect this system to return and produce a chance of showers and thunderstorms.

July 17-31

Cooler temperatures will be pulled in on the backside of the July 15-16 system. A chance of rain will develop around July 20-21 with temperatures staying in check, possibly below average.

The warmest weather the second half of July should arrive close to July 24-27(relates to April 24 & June 9). If daytime highs reach 90 or better past July 16 this would be the likeliest window. After this warm-up cooler temperatures return with a chance of showers.

Overview of July

Forecast Rainfall: Below Average (average 3.67")

Forecast Temperatures: Above Average

Discussion: With a relatively dry start to July the cities of Waukesha and Milwaukee will likely end up classified in 'moderate drought' conditions at some point during the first half of July. Precipitation in July will be centered around the middle and end of the month providing some relief. First 10 days of the month should only provide smaller chances for rain around the dome of heat, and as cold front passes around July 7. Forecast is below average precipitation, but one slow moving thunderstorm can erase the best rainfall forecast during summer.

Temperatures will be warmest the first half of July, and likely hottest the first week. Hot start will likely be enough to keep monthly departure from average warmer than normal for the 10th consecutive month.

If you have questions or comments on the July forecast please post them below. You can follow me on Twitter @jnelsonweather for more insights on the long range forecast and for weather updates throughout the day.